1. Field of the Invention
This invention relates to drilling and, more specifically, to systems and methods for determining the curvature of the wellbore by considering the bending of the drill string.
2. Description of the Related Art
Various types of drill strings are deployed in a borehole for exploration and production of hydrocarbons. A drill string generally includes drill pipe and a bottom hole assembly. The bottom hole assembly contains drill collars, which may be instrumented, and can be used to obtain measurements-while-drilling or while-logging, for example.
Some drill strings can include components that allow the borehole to be drilled in directions other than vertical. Such drilling is referred to in the industry as “directional drilling.” While deployed in the borehole, the drill string may be subject to a variety of forces or loads. Because the drill string is in the borehole, the loads are only measured at certain sensor positions and can affect the static and dynamic behavior and direction of travel of the drill string.
Either planned (directional drilling) trajectory changes, the loads experienced during drilling or formation changes can lead to the creation of a dogleg in the borehole. A dogleg is a section in a borehole where the trajectory of the borehole, its curvature changes. The rate of trajectory change is called dogleg severity (DLS) and is typically expressed in degrees per 100 feet.